Paralogous Genes of spp. Mediate Differential Sensitivity to Sterol Demethylation Inhibitors.

spp. isolates contain two paralogous genes that encode sterol 14-demethylase enzymes; however, their role in sensitivity to demethylation inhibitor (DMI) fungicides is yet to be determined. In this study, each of the two genes from and was able to rescue the function of in the yeast , demonstrating their independent function. Deletion of led to increased sensitivity to propiconazole, diniconazole, prothioconazole, cyproconazole, epoxiconazole, flutriafol, prochloraz, and difenoconazole in , and to the same fungicides and tebuconazole in , with the exception of prochloraz. Deletion of in and in made mutants increasingly sensitive to five of nine DMI fungicides tested. The results suggest species-specific, differential binding of DMI fungicides onto the two CYP51 enzymes. Pairing DMIs with different effects on and - deletion mutants resulted in synergistic effects, as determined in mycelial growth inhibition experiments. Deletion mutants showed no fitness penalty in terms of mycelial growth, sporulation, and virulence. Our study elucidates the effect of and of spp. on DMI sensitivity, suggesting that using a mixture of DMIs may improve the efficacy for anthracnose management.